1. Field of the Invention
This invention relates to a method and apparatus for measuring the hydrocarbon potential of a source rock comprising hydrocarbons and insoluble organic materials capable of generating hydrocarbons upon pyrolysis or further maturation. The apparatus is useful for field evaluation of small samples of suspected oil and gas source rock.
2. Description of the Art
Various geochemical methods have been suggested previously for determining the location and characterization of underground sources of hydrocarbons. These methods detect the presence of hydrocarbons and hydrocarbon precursors in surface or underground formations to determine the potential of such formations for the production of hydrocarbons.
In U.S. Pat. 3,508,877 and 2,451,883 a source rock comprising hydrocarbons and other organic materials which are hydrocarbon precursors is analyzed by the fluorescense of a sample prepared either by extracting the rock with a solvent or by condensing a vapor removed from the rock by heating. Neither of these methods distinguishes between hydrocarbons present in the source rock as such and organic material which can be converted in hydrocarbons upon pyrolysis or further maturation in situ.
In U.S. Pat. 4,229,181 and 4,153,415 a method and apparatus are disclosed for determining hydrocarbons initially present in a source rock sample and hydrocarbons that may be generated upon pyrolysis thereof. The method and apparatus disclosed in these patents rely upon heating the sample in a gaseous stream to selected temperatures to separately remove the hydrocarbons present in the source rock and the hydrocarbons that may be derived upon pyrolysis. The method and apparatus require a gaseous source and therefore are not as compact nor as easy to operate as is desired in the field.
In U.S. Pat. 4,149,804 and 4,149,805 a method and apparatus to determine the oil content of oil shale are disclosed. These references teach non-destructive methods which rely on the reflectance of light from a solid sample of a source rock to determine the presence of oil therein. In view of the concern of the patentees with determining the richness of oil shale, it is not surprising that this method and apparatus do not distinguish between hydrocarbons initially present in the source rock and hydrocarbons which may be generated upon pyrolysis thereof. Thus, there is no suggestion that this method and apparatus are intended to obtain information about a source rock other than an oil shale.
In view of the foregoing, it is one object of this invention to provide a facile method of analyzing a source rock to determine the hydrocarbon potential thereof, which method is capable of providing information as to both the hydrocarbons initially present and the hydrocarbons that may be generated upon pyrolysis or further maturation of the source rock.
Another object of this invention is to provide an apparatus that is useful in the field for analyzing a source rock for hydrocarbon potential and which does not require operational gases.
These and other objects and advantages of the invention will become apparent in view of the following description.